An inkjet head includes plural ink chambers in which ink is filled, plural nozzles formed in the ink chambers, and plural driving elements provided in the ink chambers and configured to cause the nozzles to discharge the ink. As the driving elements, piezoelectric elements configured to change the capacity of the ink chambers to discharge the ink or heat generating elements configured to generate air bubbles in the ink chambers to discharge the ink is used.
When a driving pulse signal is applied to the driving elements, the driving elements operate and ink droplets are discharged from the nozzles corresponding to the driving elements.
Dimensions of the plural ink chambers and dimensions of the diameters of the nozzles included in one inkjet head are not always uniform. There is also fluctuation in performance of the heat generating elements. Even if a driving pulse signal of the same voltage is applied to the plural driving elements, the volume of the ink discharged from the nozzles is not always the same. In some cases, density unevenness occurs in an image formed by the discharge of the ink.